Hermetic compressors having a high energy conversion efficiency respectively are in great demand in recent years, and generally, it is known that a low thermal conductivity material such as synthetic resin, etc. is suitable for a suction muffler used for a direct suction system of such a hermetic compressor.
A known conventional hermetic compressor is disclosed in the Official Gazette of Japanese Examined Patent Publication Hei 3-258980.
FIG. 5 is a front view of a structure of the conventional hermetic compressor, wherein a hermetic shell 101 shown in FIG. 5 is cross-cut. FIG. 6 is a side cross sectional view of the hermetic compressor shown in FIG. 5.
In FIGS. 5 and 6, the hermetic shell 101 houses an electric driving device 102 and a compressing mechanism 103 in itself. The electric driving device 102 includes a stator 104, a rotor 105, and a crank shaft 106. The compressing mechanism 103 includes a cylinder head 107, a cylinder 108, a piston 109, and a connecting rod 110. The connecting rod 110 is linked to an eccentric part 111 of the crank shaft 106 of the electric driving device 102. As shown in FIG. 6, the electric driving device 102 and the compressing mechanism 103 are elastically supported by a spring 103a in the hermetic shell 101.
As shown in FIG. 5, a suction tube 112 is fixed to the hermetic shell 101 and disposed so as to upstand inside the hermetic shell 101. The suction muffler 116 is formed with a synthetic resin material and fixed to the cylinder head 107.
The suction tube 112 and the suction muffler 116 are connected to each other via a communicating portion 113. The communicating portion 113 has a coil spring 114 and a connecting tube 115. As shown in FIG. 5, the lower end of the coil spring 114 is press-fittingly fixed to one end of the suction tube 112, and the upper end of the coil spring 114 is press-fittingly fixed to one end of the connecting tube 115. The other end of the connecting tube 115 is inserted in the suction muffler 116.
In the conventional hermetic compressor configured as described above, when the electric driving device 102 is started up and the crank shaft 106 is rotated, the motion of the crank shaft 106 is transmitted to the piston 109 via the eccentric part 111 and the connecting rod 110, so that the piston 109 makes a reciprocating motion in the cylinder 108. With such the reciprocating motion of the piston 109, a refrigerant, passing through the coil spring 114 and the connecting tube 115, is fed from the suction tube 112 into the cylinder 108 via the suction muffler 116 so as to be sucked, compressed, and discharged therefrom.
The suction muffler 116 attenuates the rippling sound generated when in suction of the refrigerant, in the cylinder 108.
In the conventional hermetic compressor configured as described above, however, the resistance of the gas flow path in the suction route to which the suction tube 112 and the suction muffler 116 are connected via the coil spring 114 is increased, causing a suction loss when a high density gas is led into the cylinder 108 from the suction tube 112 according to the circulation of the refrigerant. Consequently, the conventional hermetic compressor has confronted with problems that the volumetric efficiency is lowered and accordingly the refrigerating capacity is lowered.